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GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. See the documentation for help with subscribing to or submitting Circulars.

Search for Circulars by submitter, subject, or body text (e.g. 'Fermi GRB').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
Advanced Search

To narrow the search results, use advanced search syntax. This allows for specifying which circular field to search (submitter, subject, and/or body). For additional information, refer to the advanced search documentation.

Advanced Search Examples (click to copy):

subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"
  1. GRB 221226B: Enhanced Swift-XRT position
  2. GRB 221226B: Swift detection of a burst
  3. GRB 221226B: Fermi GBM Final Real-time Localization
  4. Swift GRB221226.95: Global MASTER-Net observations report
  5. Fermi GRB 221226A: Global MASTER-Net observations report
  6. GRB 221226A: Fermi GBM Final Real-time Localization
  7. Fermi-LAT gamma-ray observations of IceCube-221224A
  8. IceCube-221224A: BOOTES-4/MET Optical Upper Limit
  9. IceCube-221223A: BOOTES-4/MET Optical Observations
  10. Fermi-LAT gamma-ray observations of IceCube-221223A
  11. Fermi GRB 221223A: Global MASTER-Net observations report
  12. IceCube Alert 221224.04: Global MASTER-Net observations report
  13. IceCube-221224A - IceCube observation of a high-energy neutrino candidate track-like event
  14. GRB 221223A: Fermi GBM Final Real-time Localization
  15. IceCube Alert 221223.32: Global MASTER-Net observations report
  16. IceCube-221223A - IceCube observation of a high-energy neutrino candidate track-like event
  17. GRB 221221A: AGILE detection
  18. Fermi GRB 221221A: Global MASTER-Net observations report
  19. GRB 221221A: Fermi GBM Final Real-time Localization
  20. GRB 221218A: 3.6m DOT optical upper limit
  21. IceCube-221216A: No Candidate Counterparts from the Zwicky Transient Facility
  22. GRB 221216A: Detection by VZLUSAT-2
  23. GRB 221218A: MITSuME Akeno optical upper limits
  24. GRB 221218A: BOOTES-4/MET and OSN optical upper limits
  25. GRB 221218A: KAIT Optical Upper Limit
  26. IceCube-221210A: BOOTES-4/MET and Lijiang 2.4-meter Telescopes Optical Observations
  27. GRB 221215A: Fermi GBM Detection
  28. GRB 221218A: a long GRB detected by INTEGRAL
  29. Integral GRB221218.34: Global MASTER-Net observations report
  30. Fermi-LAT gamma-ray observations of IceCube-221216A
  31. IceCube-221216A: Upper limits from a search for additional neutrino events in IceCube
  32. GRB 221216A: Swift/UVOT Upper Limits
  33. GRB 221216A: Fermi GBM observation
  34. GRB 221216A: Swift-XRT refined Analysis
  35. Fermi-LAT gamma-ray observations of IceCube-221210A
  36. IceCube Alert 221216.25: Global MASTER-Net observations report
  37. GRB 221216A: AKO Upper Limit
  38. GRB 221215A: Swift-XRT observations
  39. GRB 221216A: Enhanced Swift-XRT position
  40. Swift GRB 221216A: Global MASTER-Net observations report
  41. GRB 221216A: Zadko observatory - Gingin optical observations
  42. GRB 221216A: Nanshan/NEXT optical upper limits
  43. GRB 221216A: Swift detection of a burst
  44. GRB 221216A: Fermi GBM Final Real-time Localization
  45. IceCube-221216A - IceCube observation of a high-energy neutrino candidate track-like event
  46. Fermi trigger No 692760884: Global MASTER-Net observations report
  47. GRB 221215A: Swift ToO observations
  48. GRB 221215A: Swift/BAT-GUANO arcminute localization
  49. Konus-Wind detection of GRB 221209A
  50. Fermi GRB 221215B: Global MASTER-Net observations report
  51. IPN triangulation of GRB 221209A (long)
  52. GRB 221215B: Fermi GBM Final Real-time Localization
  53. Fermi Gamma-ray Burst Monitor trigger 692760884/221215066 is not a GRB
  54. Swift GRB221215.15: Global MASTER-Net observations report
  55. Fermi trigger No 692713692: Global MASTER-Net observations report
  56. GRB 221215A: Fermi GBM Final Real-time Localization
  57. Swift Trigger 1144538 is not a GRB
  58. Fermi Gamma-ray Burst Monitor triggers 692721536/221214610 and 692713692/221214520 are not GRBs
  59. Konus-Wind detection of a burst from SGR 1935+2154 on 2022 December 13
  60. Fermi trigger No 692607435: Global MASTER-Net observations report
  61. GRB 221209A: CALET Gamma-Ray Burst Monitor detection
  62. IceCube-221210A: Upper limits from a search for additional neutrino events in IceCube
  63. GRB 221212A: Fermi GBM Final Real-time Localization
  64. Fermi GRB 221211A: Global MASTER-Net observations report
  65. GRB 221208A: AstroSat CZTI detection
  66. GRB 221211A: Fermi GBM Final Real-time Localization
  67. IceCube-221210A - IceCube observation of a high-energy neutrino candidate track-like event
  68. IceCube Alert 221210.36: Global MASTER-Net observations report
  69. GRB 221009A: MuSCAT3 observations
  70. GRB 221209A: AstroSat CZTI detection
  71. GRB 221210A: Fermi GBM Final Real-time Localization
  72. GRB 221209B: Fermi GBM Final Real-time Localization
  73. GRB 221209A: Fermi GBM observation
  74. GRB 221203C: AstroSat CZTI detection
  75. GRB 221209A: BALROG localization (Fermi Trigger 692257829 / GRB 221209243)
  76. GRB 221209A: Fermi GBM Final Real-time Localization
  77. GRB 221206B: Fermi GBM observation
  78. GRB 221206B: Swift-XRT observations
  79. GRB 221206B: Detection by GRBAlpha
  80. GRB 221206B: Swift/BAT-GUANO candidate arcminute localization
  81. GRB 221206B: Swift ToO observations
  82. Swift/BAT trigger #1143281 is not a GRB
  83. GRB 221206C: Fermi GBM Final Real-time Localization
  84. GRB 221206B: Fermi GBM Final Real-time Localization
  85. GRB 221206A: Fermi GBM Final Real-time Localization
  86. GRB 221205A: Fermi GBM Final Real-time Localization
  87. Swift GRB221204.45 AKO Upper Limit
  88. GRB 221202B: Detection by VZLUSAT-2
  89. Swift GRB221204.45: Global MASTER-Net observations report
  90. GRB 221203B: Fermi GBM Final Real-time Localization
  91. GRB 221202A: Swift/UVOT Detection
  92. GRB 221202A: Swift-BAT refined analysis
  93. GRB 221202A: VLT/FORS2 Afterglow Discovery
  94. GRB 221201A: Swift-BAT refined analysis
  95. GRB 221203A: Fermi GBM Final Real-time Localization
  96. GRB 221201A: Fermi GBM observation
  97. GRB 221202A: Swift-XRT refined Analysis
  98. GRB 221202A: LCOGT Optical Upper Limits
  99. GRB 221202A: Enhanced Swift-XRT position
  100. GRB 221202A: MeerLICHT upper limits

Advanced

Download all Circulars as a .tar.gz archive (updated once a day):
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